Fx.Elements = Fx.Base.extend({

	initialize: function(elements, options){
		this.elements = [];
		elements.each(function(el){
			this.elements.push($(el));
		}, this);
		this.setOptions(options);
		this.now = {};
	},

	setNow: function(){
		for (var i in this.from){
			var iFrom = this.from[i];
			var iTo = this.to[i];
			var iNow = this.now[i] = {};
			for (var p in iFrom) iNow[p] = this.compute(iFrom[p], iTo[p]);
		}
	},

	custom: function(objObjs){
		if (this.timer && this.options.wait) return;
		var from = {};
		var to = {};
		for (var i in objObjs){
			var iProps = objObjs[i];
			var iFrom = from[i] = {};
			var iTo = to[i] = {};
			for (var prop in iProps){
				iFrom[prop] = iProps[prop][0];
				iTo[prop] = iProps[prop][1];
			}
		}
		return this.parent(from, to);
	},

	increase: function(){
		for (var i in this.now){
			var iNow = this.now[i];
			for (var p in iNow) this.setStyle(this.elements[i.toInt()], p, iNow[p]);
		}
	}

});

Fx.Accordion = Fx.Elements.extend({

	extendOptions: function(options){
		Object.extend(this.options, Object.extend({
			start: 'open-first',
			fixedHeight: false,
			fixedWidth: false,
			alwaysHide: false,
			wait: false,
			onActive: Class.empty,
			onBackground: Class.empty,
			height: true,
			opacity: true,
			width: false
		}, options || {}));
	},

	initialize: function(togglers, elements, options){
		this.parent(elements, options);
		this.extendOptions(options);
		this.previousClick = 'nan';
		togglers.each(function(tog, i){
			$(tog).addEvent('click', function(){this.showThisHideOpen(i)}.bind(this));
		}, this);
		this.togglers = togglers;
		this.h = {}; this.w = {}; this.o = {};
		this.elements.each(function(el, i){
			this.now[i] = {};
			$(el).setStyles({'height': 0, 'overflow': 'hidden'});
		}, this);
		switch(this.options.start){
			case 'first-open': this.elements[0].setStyle('height', this.elements[0].scrollHeight+this.options.unit); break;
			case 'open-first': this.showThisHideOpen(0); break;
		}
	},

	hideThis: function(i){
		if (this.options.height) this.h = {'height': [this.elements[i].offsetHeight, 0]};
		if (this.options.width) this.w = {'width': [this.elements[i].offsetWidth, 0]};
		if (this.options.opacity) this.o = {'opacity': [this.now[i]['opacity'] || 1, 0]};
	},

	showThis: function(i){
		if (this.options.height) this.h = {'height': [this.elements[i].offsetHeight, this.options.fixedHeight || this.elements[i].scrollHeight]};
		if (this.options.width) this.w = {'width': [this.elements[i].offsetWidth, this.options.fixedWidth || this.elements[i].scrollWidth]};
		if (this.options.opacity) this.o = {'opacity': [this.now[i]['opacity'] || 0, 1]};
	},

	showThisHideOpen: function(iToShow){
		if (iToShow != this.previousClick || this.options.alwaysHide){
			this.previousClick = iToShow;
			var objObjs = {};
			var err = false;
			var madeInactive = false;
			this.elements.each(function(el, i){
				this.now[i] = this.now[i] || {};
				if (i != iToShow){
					this.hideThis(i);
				} else if (this.options.alwaysHide){
					if (el.offsetHeight == el.scrollHeight){
						this.hideThis(i);
						madeInactive = true;
					} else if (el.offsetHeight == 0){
						this.showThis(i);
					} else {
						err = true;
					}
				} else if (this.options.wait && this.timer){
					this.previousClick = 'nan';
					err = true;
				} else {
					this.showThis(i);
				}
				objObjs[i] = Object.extend(this.h, Object.extend(this.o, this.w));
			}, this);
			if (err) return;
			if (!madeInactive) this.options.onActive.call(this, this.togglers[iToShow], iToShow);
			this.togglers.each(function(tog, i){
				if (i != iToShow || madeInactive) this.options.onBackground.call(this, tog, i);
			}, this);
			return this.custom(objObjs);
		}
	}

});